Sortable silt records of intermediate-depth circulation and sedimentation in the Southwest Labrador Sea since the Last Glacial Maximum

Hoffmann, S. S.; Dalsing, Risa E.; Murphy, Sarah

doi:10.1016/j.quascirev.2018.12.028

Cited by 19 publications

(12 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…End‐member modeling of the grain size distributions allows for the decomposition into the statistically evident subpopulations, which are characteristic for different modes of sediment transport and deposition (Prins et al, ; Prins & Weltje, ). Accompanying grain size determination of the sand fraction is important to examine the possible IRD contribution to the overall grain size distributions (Hoffmann et al, ; McCave & Hall, ; Prins et al, ). The grain size data set was separated into statistically significant end‐members using the Analysize program in Matlab (Paterson & Heslop, ).…”

Section: Methodsmentioning

confidence: 99%

“…The grain size data set was separated into statistically significant end‐members using the Analysize program in Matlab (Paterson & Heslop, ). This approach has been shown to reliably determine grain size end‐members (Van Hateren et al, ) and has been applied to other marine sediment cores from the region to reconstruct changes in bottom current speed and IRD input (Hoffmann et al, ; Jonkers et al, , ; Prins et al, ).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Synchronous Changes in Sediment Transport and Provenance at the Iceland‐Faroe Ridge Linked to Millennial Climate Variability From 55 to 6 ka BP

Mirzaloo

Nürnberg

Kienast

et al. 2019

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Unique marine sediment cores retrieved from the southwestern slope of the Iceland‐Faroe Ridge (IFR), close to the main axis of the Iceland‐Scotland Overflow Water (ISOW), revealed prominent sedimentary cycles reflecting near‐bottom current dynamics, sediment transport, and deposition, coincident with Dansgaard‐Oeschger cycles and deglacial perturbations of the Atlantic Meridional Overturning Circulation. The transition between Greenland Stadials (GSs) and Greenland Interstadials (GIs) follows a distinct, recurring sedimentation pattern. Basaltic (Ti‐rich) silts were transported from local volcanic sources by strong bottom currents and deposited during GIs comparable to modern ocean circulation. Finer‐grained felsic (K‐rich) sediments were deposited during GSs, when Iceland‐Scotland Overflow was weak. Possible felsic source areas include British‐Ireland and/or Fennoscandian shelf areas. A cyclic sawtooth pattern of bottom current strength is characterized by gradual intensification during GIs followed by a sharp decline toward GSs as is documented at core sites along the flank of Reykjanes Ridge. The cores north of the Faroe Channel instead document the opposite pattern. This suggests that the near‐bottom currents along the Reykjanes Ridge are strongly controlled by the flow cascading over the IFR. Heinrich‐(like) HS‐1 and HS‐2, are characterized by the deposition of very fine felsic sediments pointing to weakened bottom currents. Distinct coarse‐grained intervals of ice‐rafted debris are absent from the sediment records, although pebble‐ and gravel‐sized ice‐rafted debris is irregularly distributed throughout the fine sediment matrix. Near‐bottom currents are considered to have a major control on the lithogenic sediment deposition southwest of the IFR and further downstream.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Synchronous Changes in Sediment Transport and Provenance at the Iceland‐Faroe Ridge Linked to Millennial Climate Variability From 55 to 6 ka BP

Mirzaloo

Nürnberg

Kienast

et al. 2019

Geochem Geophys Geosyst

View full text Add to dashboard Cite

show abstract

“…It is thus reasonable to say that any correction based on modern AR ( 230 Th/ 232 Th) for fossils older than a few thousand years might be erroneous. With respect to the Holocene samples, their 14 C and apparent 230 Th-age cluster point to their settlement more or less simultaneously with the inception of the modern-like AMOC and overall WBUC pattern (Fagel et al, 2004;Hoffmann et al, 2019), i.e., at about the start of the mid-Holocene, when LSW production started in the Labrador Sea (Van Nieuwenhove et al, 2016). A correction of 230 Th-ages based on an initial "contaminating" fraction similar to that measured in live-collected specimens may be applied as in Table S1.…”

Section: Initial Content Of Coral Samples In 230 Thmentioning

confidence: 99%

“…Were these features preventing coral growth on the mid-Labrador Slope? The question remains open until more information is available, e.g., from sortable silt measurements along the WBUC pathway (Hoffmann et al, 2019). However, sediment winnowing along the slope during intervals with a strong WBUC, results in enhanced accumulation over the underlying rise.…”

Section: Paleoceanographic Implicationsmentioning

confidence: 99%

Late Quaternary sporadic development of Desmophyllum dianthus deep-coral populations in the southern Labrador Sea with specific attention to their 14C- and 230Th-dating

Maccali

Hillaire‐Marcel²,

Ménabréaz³

et al. 2020

Marine Chemistry

View full text Add to dashboard Cite

About 70 fossil and live-collected specimens of Desmophyllum dianthus were collected from steep rocky surfaces and time-averaged assemblages at their base ("coral graveyards") in the southern Labrador Sea at depths ranging from~1700 m (Orphan Knoll) to~2200 m (Flemish Cap). Aside from stable isotope and mineralogical analysis, U-series and 14 C age determinations were performed on the samples. Fossil corals from the coral graveyards display two principal age clusters corresponding respectively to the Holocene and Marine Isotope Stage (MIS) 5c intervals. Three samples lay outside these clusters, at~13.5 ka (Bølling-Allerød),~64 ka (MIS 3) and at 181 ka (MIS 7a). The clusters are thought to record intervals with both i) high food availability, either through pelagic primary production in the overlying water column or more effectively in relation with particulate and dissolved organic carbon transport via an active Western Boundary Undercurrent (WBUC), and ii) high carbonate micrite advection by this current from more open North Atlantic coccolithophorid production areas, maintaining an aragonite saturation horizon (now at 2300 m) slightly deeper than the coral habitat (~2200 m). Attempts at estimating ventilation ages from 230 Th vs 14 C age offsets in Holocene samples failed. This is due to uncertainties about the initial 14 C-apparent age of coral skeletons and to their high initial excesses in 230 Th. This initial excess relates mostly to the scavenging of 230 Th produced by the dissolved marine U by the coral-feeding organic matter carried along the WBUC trajectory. In addition, discrete diagenetic U-fluxes can be documented in fossil samples. They are well illustrated in specimens from MIS 5c age, which depict variable excesses in 234 U vs 238 U, but similar 230 Th/ 238 U activity ratios, pointing to a recent but fractionating redistribution of uranium in the samples. These are also documented by the development of FeeMn coatings of specimens exposed at the sea floor, due to the winnowing of embedding slope sediments, with the mid-to late Holocene intensified WBUC. Such diagenetic processes are to be notably taken into consideration for the dating of pre-Holocene samples. Thus, both the initial isotopic properties of corals from this WBUC-influenced, mid-continental slope, and subsequent diagenetic effects impact their calculated ages, and blur estimates of "ventilation ages" based on their 14 C vs 230 Th-ages offsets.

show abstract

“…Grain size is a fundamental property of ocean sediments that is widely used in paleoceanographic studies, most notably as a proxy for sediment source, transport, and depositional processes. For example, variations in the grain size of marine sediments have been related to changes in paleoproductivity (Warner & Domack, 2002;Muhong et al, 2005;, fluvial discharge (Weltje & Prins, 2003;Briceño-Zuluaga et al, 2016;Carlin et al, 2019), aeolian dust input (Weltje & Prins, 2003;Holz et al, 2007;Serno et al, 2014;Stuut et al, 2014;Briceño-Zuluaga et al, 2016), and the strength and flow speed of paleo currents (e.g., McCave et al, 1995McCave et al, , 2017Tegez et al, 2014;Voigt et al, 2016;Hoffman et al, 2019). In addition, grain size is key to interpreting sediment composition (Sval'nov & Alekseeva, 2006;, and can also be used to help distinguish between different types of deep-water sediment facies (e.g., Stow & Tabrez, 1998;).…”

Section: Discussionmentioning

confidence: 99%

A multi-proxy reconstruction of sea ice extent and primary productivity during Marine Isotope Stage 11 in the Bering Sea

Thompson¹

View full text Add to dashboard Cite

Grain size is an important textural property of sediments and is widely used in paleoenvironmental studies as a means to infer changes in the sedimentary environment. However, grain size parameters are not always easy to interpret, without a full understanding of the factors that influence grain size. Here, we measure grain size in sediment cores from the Bering slope and the Umnak Plateau, and review the effectiveness of different grain size parameters as proxies for sediment transport, current strength, and productivity, during a past warm interval (Marine Isotope Stage 11, 424-374 ka). In general, sediments in the Bering Sea are hemipelagic, making them ideal deposits for paleoenvironmental reconstructions, but there is strong evidence in the grain size distribution for contourite deposits between ~408-400 ka at the slope sites, suggesting a change in bottom current transport at this time. We show that the grain size of coarse (>150 µm) terrigenous sediment can be used effectively as a proxy for ice rafting, although it is not possible to distinguish between iceberg and sea ice rafting processes, based on grain size alone. We find that the mean grain size of bulk sediments can be used to infer changes in productivity on

show abstract

Sortable silt records of intermediate-depth circulation and sedimentation in the Southwest Labrador Sea since the Last Glacial Maximum

Cited by 19 publications

References 55 publications

Synchronous Changes in Sediment Transport and Provenance at the Iceland‐Faroe Ridge Linked to Millennial Climate Variability From 55 to 6 ka BP

Synchronous Changes in Sediment Transport and Provenance at the Iceland‐Faroe Ridge Linked to Millennial Climate Variability From 55 to 6 ka BP

Late Quaternary sporadic development of Desmophyllum dianthus deep-coral populations in the southern Labrador Sea with specific attention to their 14C- and 230Th-dating

A multi-proxy reconstruction of sea ice extent and primary productivity during Marine Isotope Stage 11 in the Bering Sea

Contact Info

Product

Resources

About